The invention concerns a component for processes in semiconductor technology, made of quartz glass, having a coating whose surface consists of silicon carbide.
In the production of semiconductor components, substrate surfaces are frequently coated with silicon oxide, silicon nitride, or silicon. The known CVD (chemical vapor deposition) methods are used for this purpose. In the process, the coating materials are deposited on all the walls in the reaction space, including those of the furnace, the containers for the substrate, or the surfaces of other components. When these layers reach a certain thickness, they flake away from quartz glass surfaces, and can thereby lead to particle problems. To prevent this, the components in question must be cleaned repeatedly. To remove silicon layers, a caustic solution comprising a mixture of HF and HNO.sub.3 is normally used. However, this caustic solution also attacks the quartz glass itself. It is known that a barrier to this caustic solution can be created by coating the surface of the component with SiC.
Known from Japanese Patent Application JP 62-116728 (1987) is a discharge nozzle made of quartz glass, which serves as the gas lead-in in a reaction furnace in an epitaxy process. The known nozzle has a surface layer of silicon carbide. Between the surface of the quartz glass and the silicon carbide layer, an intermediate layer is provided, which consists of silicon or of silicon nitride.
Because of the great differences between the coefficients of expansion of quartz glass and silicon carbide or silicon, the known layers have little resistance to thermal shock. This is caused on the one hand by the relatively firm adhesion of such layers to quartz glass, and on the other hand by the differences between the coefficients of expansion of the layer material and of the quartz glass, and the resulting stresses on the coating when the temperature changes. This leads to flaking or to microcracks in the layers, which in turn reduce the resistance of the known components to the caustic solutions described above, especially to the mixture of HF and HNO.sub.3, and also reduce the prevention of diffusion of toxic semiconductor substances out of the component.